You may think caring for goldfish is simple, but what is really involved in ensuring they have a happy, healthy life?

Goldfish are a great choice for a pet, but they still require more care than many first-time goldfish owners might think, says Dr. Greg Lewbart, MS, VMD, Dipl. ACZM, professor of Aquatic Animal Medicine at North Carolina State University’s College of Veterinary Medicine. Dr. Lewbart has specialized in aquatic medicine for 25 years, and, he says, 50 to 75 percent of the cases he treats are regular goldfish or their larger family members, koi.

If you think you can plop a goldfish into a tiny little bowl with some rocks at the bottom and call it a day, you're mistaken. Here's what goldfish owners need to know to keep their pretty little pets happy and healthy.

Forget the FishbowlSmall fishbowls aren’t good homes for goldfish, says Dr. Lewbart. “A 29-gallon tank is best, and no smaller than 20 gallons,” he says, because goldfish need wiggle room. And the more volume of water in the tank, the longer it takes for the water to become polluted by fish waste, excess food, algae or bacteria — and therefore, the healthier your fish will be.

Also, Dr. Lewbart recommends putting a hood or top over the tank because goldfish like to jump. “Bad things happen to good fish,” Dr. Lewbart says. “They find a way to get into trouble.”

Goldfish are temperate fishes, says Dr. Lewbart, and not native to the United States. They’re used to temperature fluctuation, but are most comfortable around 70 degrees.

Make a Happy-Fish Shopping ListThere are many sizes and types of supplies for tanks. Dr. Lewbart recommends starting with the basics for a beginner’s system.

Power filter — A good power filter will help keep your tank clean.

Substrate — Some sort of gravel at the bottom of the tank makes it look nice.

Net — A very fine mesh net works best to scoop your fish and nudge them around the tank as needed during cleaning. But don’t overhandle your fish, Dr. Lewbart cautions.

Thermometer — Knowing the current temperature of the water, so that, if needed, you can make adjustments is critical in keeping your fish healthy and happy.

Heater back up — While your goldfish tank doesn’t need a heater, if you lose heat in your home for some reason, a backup heater can keep the water from getting too cold.

Dechlorinating agent — Most municipal water will have a bit of chlorine in it, Dr. Lewbart says, so make sure you treat the water with a dechlorinating agent when you first set up the tank and each time you add new water.

Aquarium salt — Goldfish like a little salt in their water, says Dr. Lewbart. It helps with transition and stress and can even help keep some health issues at bay. Read instructions on the package to avoid oversalting.

Let’s Talk NumbersHow many fish should you have in a tank? “I’d start with four or five decent-sized goldfish,” advises Dr. Lewbart. Although, he says, there are lots of formulas out there for number of fish per gallon, he usually recommends one fish for every five gallons of water. But remember that first, single fish needs at least the 20-gallon tank recommended above.

And if you want just one fish, that’s fine too. “Goldfish are very sociable, but don’t require or need companionship,” says Dr. Lewbart. “They’re not aggressive fish and typically leave each other alone," he says.

Keep Those Fish AliveI remember going through a lot of goldfish when I was a kid. It seemed to me that the little orange guys just weren’t super hardy and expired pretty quickly. According to Dr. Lewbart, this isn’t the case if they’re cared for properly. In fact, he says, he’s treated goldfish as old as 14 years old.

So, what does it take to keep a goldfish thriving for years?

Quarantine Your Fish — The most important thing you can do to keep your pet fish alive and healthy is to not introduce any new fish to the tank without a quarantine period. There are several infectious diseases that your new fish may have, as well as ich, which is a common but deadly parasite. Introduce a new, infected fish and all your current fish will likely be goners.

When you bring home a new fish, put him in a separate tank for at least 30 days. If he looks good and healthy after a month, you can add him into the tank with his new friends.

Don’t Overfeed Your Fish — Overfeeding leads to contamination of the water, both with excess food and fish waste.

Dr. Lewbart especially warns about leaving your fish in the care of someone else while you’re on vacation. Other people won’t be as diligent as you will be about the right amount of food and the state of the water. “But they looked hungry!” is a common excuse for overfeeding. If you must have someone watch your fish, pre-measure food in labeled containers and be adamant about what to feed them.

Change the Tank Water Regularly — Water-quality management is critical to the health and well-being of your fish. This is one reason a larger tank is so important. Smaller tanks get polluted much faster because there’s not as much water volume to dilute contaminants.

Dr. Lewbart advises siphoning a third of the tank water and replacing each month with water treated with a dechlorinating agent. “Keeping the water turnover consistent is very important,” he stresses.